4x AA battery holder / case

Sure... You can buy this thing for 76 euro cents at ALiExpress but hey... we'r makers so I designed this classic one which fits by the way in my OTTO robot.
For the + contacts I used 4 pushpins (which you can push through the holes with a hot solder iron) and for the - some springs I had laying around and Hot Glued them in to the little rings to center them. I assume you can figure out the rest yourself?

Have fun!